Radar antenna system



y 10, 1960 1.. REINHARD ETAL 2,936,452

RADAR ANTENNA ,SYSTEM Filed Sept. 10, 1956 RADAR ANTENNA SYSTEM Louis Reinhard, Lncerne, and Hans Klauser, Zurich, Switzerland, assignors to Albiswerk Ziirich A.G., Zurich, Switzerland, a Swiss corporation Application September 10, 1956, Serial No. 608,742

Claims priority, application Switzerland December 14, 1955 6 Claims. (Cl. 343-757) Our invention relates to a radar antenna system comprising a reflector, for instance of parabolic shape, and a primary radiator movable on a circle about the focal point of the reflector in a plane perpendicular to the direction of propagation of the electromagnetic Waves.

In such antenna system, the circular movement of the primary. radiator about the reflector focal point serves to produce a rotating directional radar beam which is deflected out of the axis of symmetry of the reflector. The amount of deflection may amount to about one degree and the number of rotations per minute may be about I 1,800, .for instance. The primary radiator is fed through a wave-guide system comprising a stationary portion and a movable portion, the radiator being mounted on the free end of the movable portion. In the antenna assemblies of this kind now in use, the movable portion of the waveguide system consists of a straight Waveguide conductor. This conductor is connected with a driving mechanism located behind the reflector and is so journaled that the conductor axis, in operation, definesa cone whose apex lies behind the crest point of the reflector. Located at the same apex is a wave-guide coupling 'which articulately joins the movable portion with the stationary portion of the wave-guide system. For avoiding mechanical losses, the coupling should consist of two mechanically separate coupling portions; and for increasing the power-transmitting capacity of the waveguide system the interior of the system is preferably subjected to super-atmospheric pressure.

The construction of such an antenna assembly under the above-mentioned conditions involves various difliculties. In this respect, the desired maintenance of super- Sttes Patent atmospheric pressure within the wave-guide system poses a particular problem. Above all, the antenna assemblies of this type heretofore available left much to be desired with respect to the provision of a gas-tight seal for the wave-guide coupling.

It is among the objects ofour invention to eliminate these difficulties.

To this end, and in accordance with a'feature of our invention, the wave-guide coupling, the driving mechanism for the movable portion of the wave-guide system,

-Patentetl May 16, 196i? prevents an abrupt pressure drop in the wave-guide system in the event of unintentional failure of the compressor and ofiers also an advantage in constructional and operational respects by permitting the compressor to be coupled with the driving mechanism for the primary radiator. In this manner, reliable maintenance of the super-atmospheric pressure is secured even in intermittent operation.

The foregoing and other objects, advantages and features of the invention will be apparent from the embodiment of a radar antenna structure part-sectionally illustrated by way of example on the drawing and described in the following.

The antenna proper of the illustrated assembly consists of a primary radiator 1 and. a reflector 2, for instance of paraboloidal shape. The axis of symmetry of the reflector is indicated at 3. The primary radiator 1 is energized through a wave-guide system composed of a stationary portion and a movable portion. The movable portion consists of a straight, tubular wave-guide conductor 4 whose longitudinal axis is indicated at 5. The primary radiator 1 is mounted on the free end of the straight conductor 4. The other end of conductor 4 is connected with the stationary wave-guide portion 8 by two mechanicaliy separate portions 6 and 7 of a waveguide coupling which is located within a hermetically sealed housing 9. The wave-guide portions 4 and 8 extend through the housing walls to the outside and are gas tightly sealed with the housing wall. For this purpose, a sealing ring 10 is disposed between the movable waveguide conductor 4 and the housing 9. The interior space of housing 9 is in communication with the interior of the wave-guide system through openings 11, 12 and 13 in the coupling portions 6 and 7 so that the pressure pro duced within the housing 9 is also effective in the interior of the wave-guide system.

The primary radiator 1 is capable of translatory motion on a circle about the focal point of the reflector 2 in a plane perpendicular to the propagating direction of the electromagnetic Waves. For this purpose the movable waveguide conductor 4 must be so driven that its axis 5 defines the surface of a cone, without notation of the radiator 1 about the axis 5, the cone axis being coincident with the symmetry axis 3 of the reflector 2. To this end, the movable conductor 4 is journaled in housing 9 by means of a universal joint and is connected with an eccenhis 15 by means of a rod 14.which is fastened to the coupling portion 6 and extends coaxially to the waveconductor 4, the eccentric 15 being revolv'able about the symmetry axis 3 of the reflector 2. The universal joint is composed of a fixed gimbal ring 16 mounted on housing 9, an inner ring 17 seated upon the coupling portion as well as a compressor for the production of positive pressure in the interior of the wave-guide system, are all mounted within a hermetically sealed housing. which serves as an air pressure chamber.

As a result, the need for a seal at the wave-guide coupling is eliminated. Instead, a gas-tightly sealed passage of the movable wave-guide portion through the housing is necessary; but such a sealed passage does not offer particular ditficulties. In addition, the invention affords a number of other essential advantages. For instance, the entire driving mechanism is protected by the hermetically sealed housing from extraneous influences particularly moisture, dust, and sand. By virtue of the super-atmospheric pressure within the housing, cooling of the drive motor is improved in a simple manner. The

air-pressure chamber formed by the sealed housing also 6, and a movable gimbal ring 18 located between rings 16 and17 and provided with four ball bearings 19 which are uniformly distributed over the periphery of ring 18, only two ball bearings 19 being visible in the drawing. The inner races of the ball bearings 19 are seated upon respective pivot pins 20. Each two diametrically opposite pivot pins 20 are mounted on the outer gimbal ring 16 as shown, and the other two pivot pins: are connected with the inner ring 17.

Mounted on rod'14 is a body 21 which serves as a balancing mass. The eccentric 15 is coupled with an electric drive'motor 24 through two intermeshing spur gears 22 and 23. Also coupled with the drive motor 24 and directly mounted thereon is a piston compressor 25 for the production of the desired superatmospheric pressure within the Wave-guide system. The compressor 25 has a suction duct 26 in communication with the ambient air, and a pressure duct 27 communicating with the interior of housing 9. The entire driving mechanism for the wave conductor 4, comprising the components 14,15

r v r 3 and'21 to 24, as well as the piston compressor 25, is mounted within the housing 9 which, aside from mechanically protecting these components, also operates as an air pressure chamber for continuous maintenance of super-atmospheric pressure within the wave-guide system.

In general, aradar antenna assembly of the type described is provided with additional components or auxiliaries which are preferably also mounted within the housing 9, for instance a generator for producing a reference voltage defining the instantaneous position of the primary radiator.

it will be obvious to those skilled in the art, upon a study of this disclosure, that antenna assemblies according to our invention may be modified in various ways, particularly with respect to the shape, design and arrangement or" the individual components, and hence may be embodied in devices other than the one particularly illustrated and described, without departing from the essence of the invention and within the scope of the claims annexed hereto.

We claim:

1. A radar antenna system, comprising a housing structure forming a gas pressure chamber, a reflector outside the housing, the reflector having a focal point, a Wave guide structure comprising a movable hollow structure extending from within to without the housing structure, a universal pivot means for the movable hollow wave guide structure, the latter being movable on the universal pivot means to describe a conoidal surface about the axis of symmetry of the reflector, a primary radiator mounted onthe outer end portion of the movable hollow structure, sealing means between the movable hollow wave guide structure and the housing structure at the region of entry of the former into the latter, the universal pivot being mounted within the housing structure at a location inwardly of the said region of entry, drive transmitting means within the housing structure and connected tothe movable hollow wave guide structure to move it on the universal pivot, the primary radiator being thereby moved about the focal region of the reflector, located on said axis of symmetry, said drive transmitting means including a hollow drive transmitting member that is rigidly connected to and has an opening communicating with the movable hollow wave guide structure, the wave guide structure further including a hollowed structure that is stationary with respect to the housing structure and that extends from within the hollow drive transmitting member to the outside of the housing structure, the interior of the stationary hollowed wave guide structure communicating with that of the movable hollow waveguide structure through the said opening of the hollow drive transmitting member, means to provide gas pressure within the housing, the gas communicating-with the interior of the hollow drive member with the interior of the movable wave guide structure, said means to provide gas pressure comprising a compressor within the pressure housing structure having-an intake outside of the pressure housing structure, and motor means to drive the hollow drive member and the compressor, within the pressure housing structure.

2. A radar antenna system, comprising a housing structure forming a gas pressure chamber, a reflector outside thehousing, the reflector having a focal point, a Wave guide structure comprising a movable hollow structure extending from Within to without the housing structure, a universal pivot meansrfor the movable hollow waveguide structure, the latterbeing movable on the universal pivot means to describe a conical surface about'the axis of symmetry of the reflector, a primary radiator mounted on the outer end portion of the movable hollow structure,'s ealing means between the movable hollow wave guide structure and the housing structure at the region of entry of the former into the latter, the universal pivot being mountedwithin the housing structureat a location inwardly of the said region ojfentry, drive transmitting means within i the housing structure and connected to the movable hollow wave guide structure to move it on the universal pivot, the primary radiator being thereby moved about the focal region of the reflector, located on said axis of symmetry, said drive transmitting means including a hollow drive member that is rigidly connected to and has an opening communicating with the movable hollow Wave guide structure, the wave guide structure further including a hollowed structure that is stationary with respect to the housing structure and that extends from within thehollow drive transmitting member to the outside of the housing structure, the interior of the stationary hollowedwave guide structure communicating with that of the movable hollow wave guide structure through the said opening of the hollow drive transmitter member, the universal pivot means comprising means mounted about the hollow drive transmitting member, means to provide gas pressure within the housing, the gas communicating with the interior of the hollow drive transmitting member and the interior of the wave guide structure, said means to provide gas comprising a compressor located within the pressure housing structure and having an intake outside of the pressure housing structure, said drive transmitting means including an eccentric drive, for the hollow drive member, within the pressure housingstructure, and common power means, for the said drive transmitting means and the compressor, within said pressure housing structure. V

3. A radarantenna system, comprising a'housing structnre forming a gas pressure chamber, a parabolic'reflec tor outside the housing, the reflector having a focal point, a 'wave guide structure comprising a movable hollow structure extending from within to without the housing structure, a universal pivot means for the movable hollow .wave guide structure, .the latter being movable on the universal pivot means to describe a conoidal surface about the axis of symmetry of the reflector, a primary radiator firmly mounted on the outer end portion of the movable hollow structure, sealing means between the movable hollow structure and the housing structure at the region of entry of the former into the latter, the universal pivot being mounted within the housing structure Ma location inwardlyof the said region of entry, drive transmitting means within the housing structure and connected to the movable hollow wave guide structure to moveit on 'the universal pivot, the primary radiator being thereby moved about the focal region of the reflector, located on said axis of symmetry, said drive transmittingmeans including a h ollow drive member that is rigidly connected to and has an opening communicating with the movable hollow structure, the wave guide structure including a hollowedstructure that is stationary with respect tothe housing structure and that extendsfrom within the hollow drive transmitting member to the outside of the housing structure the interior of the stationary hollowedtwave guide structurebeing at least partly in alignment with and communicating with that of the movable, hollow wave guidestructure through thesaid opening of the'hollow drive transmitting member, the universalpivot comprising gimbalmeans mounted about the hollow drive transmitting member, means to provide gas pressure within the housing, the gas communicating with the interior of the hollow drive transmitting member andthence with the interior ofthe movable wave guide structure, said means to provide .gas comprising a compressor within the pressure housing structure having an intake outside of the pressure housing structure, said drive transmitting means in: cluding .eccentric. drive transmitting means for the hollow. drive member, within the pressure housing vstructure, common motor means, for driving the said drive transmitting means and the compressor, within said pressure housing structure, and a pair of adjacent,,s p aced ringsrespectively mounted on the interior of thehollow drive member and .on the exterior of the adjacent end of the stationary waveguide structure, said ringsco- .drive member, with the interior of the pressure housing structure.

4. A radar antenna system, comprising a reflector having a focal point, a primary radiator adapted for motion about said focal point within a plane perpendicular to the reflector axis, a hollow wave-guide assembly having a stationary member and a movable member and a waveguide coupling electrically interlinking said two members, said radiator being firmly mounted on said movable waveguide member, a housing forming a pressure chamber, said coupling being mounted in said housing, said respective stationary and movable wave-guide members each extending from within to the outside of said housing, pivot means for the movable wave guide member within said housing, sealing means between the movable wave guide member and the housing, drive means mounted in said housing and mechanically connected with said movable wave-guide member for imparting said motion to said radiator, and a compressor having its pressure side in free communication with the interior of said housing, the interior of said hollow wave-guide system communicating with the interior of said pressure chamber, said compressor being mounted within said housing and being mechanically connected with said drive means to be driven there from.

5. A radar antenna system, comprising a reflector having a focal point, a primary radiator adapted for motion about said focal point within a plane perpendicular to the reflector axis, a hollow wave-guide assembly having a stationary member and a movable member and a waveguide coupling electrically interlinking said two members, said radiator being firmly mounted on said movable waveguide member, a housing forming a pressure chamber, said coupling being mounted in said housing, said respective stationary and movable wave-guide members each extending from within to the outside of said housing, pivot means for the movable wave guide member within said housing, sealing means between the movable wave guide member and the housing, drive means mounted in said housing and mechanically. connected with said movable wave-guide member for imparting said motion to said radiator, and a compressor having its pressure side in free communication with the interior of said housing, the interior of said hollow waveguide system communicating with the interior of said pressure chamber, said compressor being mounted within said housing and being mechanically connected with said drive means to be driven therefrom, and having a suction duct extending to the outside of said housing and open to ambient air.

6. A radar antenna system, comprising a reflector having a focal point, a primary radiator adapted for motion about said focal point within a plane perpendicular to the reflector axis, to produce a rotating directional radar beam which is deflected out of the axis of symmetry of the reflector, a hollow wave-guide system having a hollow stationary member and a hollow movable member and a wave-guide coupling electrically interlinking said two members, said coupling comprising relatively displaceable coupling members, said radiator being mounted on said movable wave-guide member, a sealed housing forming a gas pressure chamber, said coupling being mounted in said housing, said respective stationary and movable wave-guide members each extending from within to the outside of said housing, means for movably supporting the movable wave-guide member, substantially gas-tight sealing means between the movable wave-guide member and the housing, drive means mounted in said housing and mechanically connected with said movable wave-guide member for imparting said motion to said radiator, and a compressor having its pressure side in free communication with the interior of said housing, the interiors of said members of the hollow wave-guide system communicating with each other, and communicating with the interior of said pressure chamber, the latter communication being through a restricted passageway, the gas-pressure chamber formed by said housing tending to operate against abrupt pressure drop in the wave-guide system, said compressor being mounted within said housing and being mechanically connected with said drive means to be driven therefrom, and having a suction duct extending to the outside of said housing;

References Cited in the file of this patent UNITED STATES PATENTS 2,419,895 Hefele Apr. 29, 1947 2,535,699 Schnell Dec. 26, 1950 2,605,420 Jatfe July 29, 1952 2,617,029 Plummer et a1. Nov. 4, 1952 2,646,508 Fisher July 21, 1953 2,783,440 Lovick Feb. 26, 1957 

